1. Field of the Invention
This invention relates to a room temperature vulcanizable silicone elastomer.
2. Description of the Prior Art
Aminoxysilicon compounds are known in the art as shown by U.S. Pat. No. 3,441,583 issued to Robert A. Murphy which is hereby included by reference to show the aminoxysilicon compounds and a method of their preparation. These aminoxysilicon compounds can be used as crosslinkers in silicone elastomer compositions as shown by Boissieras et al. in U.S. Pat. No. 3,359,237 and U.S. Pat. No. 3,429,847. The aminoxysilicon compounds are also known for making low modulus organopolysiloxane elastomers as described by Murphy in U.S. Pat. No. 3,341,486. Murphy describes his low modulus organopolysiloxane elastomers as being a mixture of a silanol-terminated polydiorganosiloxane and a mixture of a difunctional aminoxysilicon compound and a polyfunctional aminoxysilicon compound. Although these low modulus organopolysiloxane elastomers have many useful properties, the compositions are primarily useful as two package products. Additionally, the aminoxy organopolysiloxane compositions are not very storage stable because of scission of the polydiorganosiloxane chain. One method to reduce the chain scission problem is described by Ashby in U.S. Pat. No. 3,592,795 in which aminoxy silyl groups terminate organic polymers. However, by changing the polymer backbone from organosiloxane to organic, the resulting product is no longer a silicone elastomer but it is basically an organic elastomer.
A storage stable room temperature vulcanizable silicon elastomer composition which cured to a low modulus silicone elastomer was described by Toporcer et al. in U.S. Pat. No. 3,817,909 wherein a mixture of a hydroxyl endblocked polydiorganosiloxane having a viscosity of 70 to 50,000 cs. at 25.degree. C., a silane of the formula ##STR2## where R.sup.4 is methyl, vinyl or phenyl and R.sup.5 is methyl, ethyl or phenyl, and an aminoxysilicon compound, optionally containing a non-acidic, non-reinforcing filler was disclosed. Although the compositions described by Toporcer et al. are stable and useful as described, improvements were still sought such as with the freeze-thaw characteristics and slump characteristics.